Chart of the day: Onset of a super rain storm in Argentina.
Fig. 1: A stalled frontal system over northeast Argentina coupled with waves of upper level short wave energy ignites a super rain storm.
Discussion: A frontal system separating hot and humid air to the north from increasingly cooler air to the south coupled with at least 2 passing upper level troughs over the next several days will cause an excessive rainfall event affecting northeast Argentina to southeast Brazil. Thunderstorms percolate over wet soil moisture after passage of the short wave energy prolonging the excessive rainfall event. The GFS remains most aggressive with over 12 in. of rain possible (Fig. 2). The ECM is not quite as excessive forecasting 9+ in. (Fig. 3). The event rivals or exceeds the infamous super rain storm of February 2016 (Fig. 4).
Fig. 2-3: The GFS indicates a 120-hour rainfall forecast of 12+ in. on the northeast Argentina border. The ECM forecast is in the 9-inch range.
Fig. 4: Late summer season excessive rainfall event in northeast Argentina from February 2016